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Revealing The Last Slice Of Spectrum


Developments to Watch

REVEALING THE LAST SLICE OF SPECTRUM

HUMANS SEE WHAT WE SEE because the "film" in the backs of our eyes responds to certain frequencies of light. But what's visible to us is only a tiny slice of the light suffusing the world. The rest would be unseen without the likes of X-ray film, which responds to higher frequencies than human eyes, and infrared film, which captures frequencies too low for the eye.

At still lower frequencies, there's an almost untapped region of light that might prove even more revealing than X-rays, says Xi-Cheng Zhang, an associate professor of physics at Rensselaer Polytechnic Institute. He has devoted years to harnessing this slice of the spectrum, which is sandwiched between infrared and microwave radiation. This "terahertz" radiation passes through many objects, much like X-rays, and can theoretically produce internal views that are difficult or impossible to see with X-rays or other radiation. Examples include pictures of diseased tissue, or plastic bombs in suitcases.

The missing piece of the puzzle was "film" to register terahertz images. That's what Zhang has devised. It's a zinc-telluride crystal from which images can be extracted with a laser pickup similar to laser readers in CD-ROM players. Now, "the last unexplored region of the spectrum [can be] declared open for business," says Kevin R. Stewart, chairman of Molecular OptoElectronics Corp. in Watervliet, N.Y. Founded in 1993 after Stewart left General Electric Co.'s research lab in Schenectady, N.Y., MOEC has an exclusive license on Zhang's technology.EDITED BY NEIL GROSS Otis PortReturn to top

THEY'LL KNOW IF YOU'VE FALLEN AND CAN'T GET UP

SICK OF PAGERS AND VOICE mail? You ain't seen nothin' yet. For three years, employees at Executone Information Systems Inc. in Milford, Conn., have been clipping smart badges to their clothes every morning. The badges send infrared signals to smoke-detector-like re-ceivers in offices and hallways. These relay everyone's whereabouts to a computer linked to the phone system. Call Elvina Presley in marketing, and her message system will tell you she has left the building or is in a meeting, and will offer to forward your call.

Now, Executone is working with 27 hospitals to tailor the system for homebound patients by adding a variety of medical sensors. Information on heart rate, temperature, or glucose level can be transmitted continuously to a patient's home PC. The computer analyzes the data and forwards it to doctors over phone wires.

This idea could get a boost from a clever finger ring under development at Massachusetts Institute of Technology. It has optical sensors that monitor pulse and blood oxygen levels, and it communicates with a PC over radio waves.EDITED BY NEIL GROSS Susan JacksonReturn to top

YOUR FACE IS YOUR PASSWORD

IT TAKES A PASSWORD TO boot up most office PCs these days. Logging onto a network calls for another. Then comes voice mail, E-mail, online services, and restricted Web pages--not to mention personal ID numbers on phone, credit, and cash cards.

It's a lot to remember. But at least some of these could be replaced by a digital snapshot of your face, says Bob Hughes, president and CEO of Viisage Technology in Littleton, Mass. Three years ago, his company licensed a powerful face-recognition algorithm from Massachusetts Institute of Technology. Unlike competing products based on complex "neural networks," the Viisage system snaps a digital picture and converts key facial features--say, the distance between the eyes--into a series of numerical values. These can be stored on an ID or ATM card as a simple bar code and don't take up much room in a computer database. Searching through tens of thousands of faces is a snap, says Hughes. Welfare agencies in Massachusetts have started using the system to reduce duplicate applications and other types of fraud.EDITED BY NEIL GROSSReturn to top


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